The Besançon Galaxy model was used to compare the infrared colour distribution of synthetic stars with those from 2MASS observations taking the selection function of the data into account , in order to study the shape of the stellar halo of the Milky Way , with complemetary spectroscopic data from SDSS-III/APOGEE survey .
Furthermore , we compared the generated mock metallicity distribution of the Besançon Galaxy model , to the intrinsic metallicity distribution with reliable stellar parameters from the APOGEE Stellar Parameters and Chemical Abundances Pipeline ( ASPCAP ) .
The comparison was carried accross a large volume of the inner part of the Galaxy , revealing that a metal-poor population , [ M/H ] < -1.2 dex , could fill an extended component of the inner galactic halo .
With this data set , we are able to model a more realistic mass density distribution of the stellar halo component of the Milky Way , assuming a six-parameters double power-law model , and reconstruct the behaviour of the rotation curve in the inner part of the Galaxy .